Project Summary/Abstract Lewy body disorders include Parkinson?s Disease Dementia (PDD) and Dementia with Lewy Bodies (DLB). DLB is particularly problematic since it is often not appreciated until late stages, and often is admixed pathologically with concomitant Alzheimer?s disease (AD). Clinical care and the design of symptomatic and disease modifying trials for DLB would benefit from earlier diagnosis and reduced pathological heterogeneity. Thus, it is important to identify the extent to which Lewy Body versus AD pathology contributes to the phenotype and underlying biology of DLB, and to discover new molecular targets that specific to DLB. Clinically, we are uniquely poised to recruit a multiethnic cohort of DLB patients derived from both the local /metropolitan community, the Alzheimer?s Disease Research Center [ADRC], and the broader practice settings of the Aging and Dementia, Movement Disorders, and primary care programs at Columbia University. We will capture the continuum of cognitive impairment and extrapyramidal signs that exist in DLB. In Aim 1, we will identify and recruit an ethnically diverse (White, Hispanic, African American) cohort of 40 DLB patients per year for years 1-4, who will be followed semi-annually. We will administer the NINDS Parkinson?s Disease Biomarkers Program (PDBP) battery, the NIA National Alzheimer Coordinating Center (NACC) UDS3 with the new DLB module. In Aim 2, we will perform RNA gene expression and epigenetic (DNA methylation) profiling on dissected brain tissue from our Columbia University brain bank including cases with pathologically defined Lewy Body Disease with AD pathology (DLB/AD) and without significant AD (DLB), cases with AD, and controls to identify Lewy body specific differences primarily by comparing DLB/AD and AD. In Aim 3, we will use expression data from Aim 2, to develop biomarker assays in blood and CSF, including at RNA and protein levels. This aim will first utilize plasma from cases who have autopsy proven diagnosis, and will then be expanded to samples with clinical diagnoses.